Example:

Multiply: (3x + 4y)(2x + 5y)

Step 1 (Distribute): 3x*2x + 3x*5y + 4y*2x + 4y*5y

Step 2 (Multiply): 6x² + 15xy + 8xy + 20y²

Step 3 (Combine like terms): 6x² + 23xy + 20y²